1. Field of the Invention
The present invention relates to a method for the separation of uranium isotope compounds in which one isotope has been selectively converted by means of laser radiation within a gas jet having supersonic velocity.
2. Description of the Prior Art
A large number of isotope separation methods have already been proposed, in which the so-called isotope shift in the spectra of the uranium compounds was utilized for the isotope-specific excitation through irradiation with narrow-band laser radiation. In this connection, reference is made to German Published NonProsecuted Patent Application No. 2 447 762 (corresponding U.S. application Ser. No. 612,213) as well as German Application No. P 26 59 590 (corresponding U.S. application Ser. No. 862,504). There, adiabatic expansion of the gaseous isotope mixture is proposed whereby supersonic velocity is achieved and cooling to temperatures of about 30 to 50 K. is effected in the process. By means of this measure it is possible to cover the Q-branch of the V.sub.3 -band in the spectrum of the UF.sub.6 of the one uranium isotope practically without influencing the other. The excitation obtainable in this manner of only the one isotope compound makes it possible, for instance, to chemically react the same with a simultaneously introduced reaction partner, so that therefore a reaction product, for instance, UF.sub.5, a solid substance, is formed. These reaction products which initially have the nature of aerosole, agglomerate and thus form particles of larger mass than that of the molecules which do not participate in the reaction.
From the so-called separation-nozzle method it is known to utilize for the isotope separation the mass difference between uranium 235 and uranium 238, in the compound UF.sub.6. The gas flow is conducted in nozzle-like canals and is deflected therein, so that under the influence of the centrifugal force or the mass inertia, a redistribution of the uranium isotope molecules of different specific gravity takes place. The gas jet depleted of the desired uranium isotope is collected separately from the correspondingly enriched gas jet by means of a mechanical peeler.
In view of the very small mass differences, the efficiency of such a separating stage is very low, so that a large number of such separating stages must be connected in series to achieve the enrichment to 3% uranium 235 required for light-water reactors.
The degree of enrichment obtainable by isotope-specific laser excitation is substantially higher and under some conditions yields the desired enrichment in one stage. However, it is important there to separate the reaction products enriched, for instance, with uranium 235, rapidly from the remaining gas flow, as the selectivity of this method could be reduced by fluorine exchange between reaction products, i.e., UF.sub.5 and UF.sub.6. Utilizing the centrifual forces by means of flow deflection has been proposed already in Patent Application No. P 26 59 590 and corresponding U.S. application Ser. No. 862,504; the flow canal was confined there by solid walls. However, this method can bring with it difficulties of an equipment nature, since the confining walls must be suitable for the temperature of the gas jet and, under some conditions, additional measures for influencing the boundary layers become necessary.